package com.http;

import java.security.MessageDigest;

/**
 * 
 * @ClassName:MD5ToolMd5加密字符串工具
 * @Description:TODO
 * @author zhuw
 * @date 2013-4-25 上午10:09:14
 */
public class MD5Tool
{
	
	
    //十六进制下数字到字符的映射数组  
    private final static String[] hexDigits = {"0", "1", "2", "3", "4",  
        "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};  
	 public static String md5(String originString){  
	        if (originString != null){  
	            try{  
	                //创建具有指定算法名称的信息摘要  
	                MessageDigest md = MessageDigest.getInstance("MD5");  
	                //使用指定的字节数组对摘要进行最后更新，然后完成摘要计算  
	                byte[] results = md.digest(originString.getBytes());  
	                //将得到的字节数组变成字符串返回  
	                
	                return  byteArrayToHexString(results);  
	            } catch(Exception ex){  
	                ex.printStackTrace();  
	            }  
	        }  
	        return null;  
	    }  
	
	   /**  
	     * 转换字节数组为十六进制字符串 
	     * @param     字节数组 
	     * @return    十六进制字符串 
	     */  
	    private static String byteArrayToHexString(byte[] b){  
	        StringBuffer resultSb = new StringBuffer();  
	        for (int i = 0; i < b.length; i++){  
	            resultSb.append(byteToHexString(b[i]));  
	        }  
	        return resultSb.toString();  
	    }  
	      
	    /** 将一个字节转化成十六进制形式的字符串     */  
	    private static String byteToHexString(byte b){  
	        int n = b;  
	        if (n < 0)  
	            n = 256 + n;  
	        int d1 = n / 16;  
	        int d2 = n % 16;  
	        return hexDigits[d1] + hexDigits[d2];  
	    }  
	
	  
	  
	  
	  
	public static  String preCat(String[] infoArray){
		
		if(infoArray.length==1){
			return infoArray[0];
		}else {	
			
			StringBuffer sb=new StringBuffer();
			for(int i=0;i<infoArray.length;i++){
				if(i==infoArray.length-1){
					sb.append(infoArray[i]);
				}else{
					sb.append(infoArray[i]).append("/t");
				}
			}
			return sb.toString();
			
		}
		
		
	}
	
    
   
}